The present invention relates to a remover solution for photoresist used in the manufacturing process of semiconductor devices such as ICs, LSIs and the like for removing the positive-or negative-working photoresist layer after fine processing on the semiconductor wafers. More particularly, the invention relates to a remover solution for photoresist having excellent removing power for various kinds of photoresists and having no or little problem of safety in respect of danger of fire and explosion.
To give an outline of the conventional process of manufacturing of semiconductor devices such as ICs, LSIs and the like, a substrate plate, such as a semiconductor silicon wafer, is first provided with a thin film of an oxide, such as silicon oxide, on the surface and then with a uniform coating layer of a photoresist composition. Thereafter, the photoresist layer is exposed to light pattern-wise and then developed to form a patterned photoresist layer which serves as a protecting mask for the subsequent selective etching of the underlying oxide film and other processing procedures. Finally, the patterned photoresist layer is removed completely.
The photoresist layer in the above mentioned last step is removed using a remover solution having a dissolving or decomposing power therefor. Various kinds of remover solutions have been hitherto proposed and actually used including acids and acid mixtures such as concentrated sulfuric acid, fuming sulfuric acid, mixtures of sulfuric acid and hydrogen peroxide and others capable of decomposing the photoresist layer, especially, at an elevated temperature and organic solutions of a surface active agent such as alkylbenzene sulfonic acid dissolved in an organic solvent such as phenols, halogenated hydrocarbons and the like capable of dissolving the photoresist layer.
A serious problem involved in the use of a strong acid such as concentrated sulfuric acid or fuming sulfuric acid as the former class of the remover solutions is of course dangers of the acid to human body and the danger is larger when the acid is used at an elevated temperature as is mostly the case in the use of these acids so that utmost care should be taken to avoid hazards. The remover solutions of the latter class are also not free from the problem of safety due to the toxicity of the solvents such as phenols and halogenated hydrocarbon solvents against human body as well as the danger of fire or explosion. Moreover, such an organic solution is disadvantageous in respect of the environmental pollution when waste solutions are discharged to a public waterway so that the process can be run only with expensive facilities for the disposal of the waste solutions.
Various proposals and attempts have been made of course to solve these problems in the conventional remover solutions. Some of the improved remover solutions so far proposed include mixtures of an alkylbenzene sulfonic acid of which the overall number of carbon atoms in a molecule is 10 to 20 and a non-halogenated aromatic hydrocarbon solvent having a boiling point of 150 .degree. C. or higher as disclosed in Japanese Patent Kokai 51-72503, mixtures of a surface-active alkyl aryl sulfonic acid of which the overall number of carbon atoms in a molecule is 10 to 20, a hydrotropic aromatic sulfonic acid having 6 to 9 carbon atoms in a molecule and a non-halogenated aromatic hydrocarbon solvent as disclosed in U.S. Pat. No. 4,165,294 and mixtures of an organic sulfonic acid and an effective amount of 1,2-dihydroxybenzene with admixture of a polar or non-polar organic solvent as disclosed in European Patent EU-A 0119337.
These remover solutions according to the above mentioned proposal, however, are not quite satisfactory in respect of the removing power of photoresist layers although they are free from the disadvantages in respect of the toxicity to workers, danger in working and troubles in the disposal of waste solutions owing to the absence of phenols and halogenated hydrocarbon solvents in their formulation.